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To achieve their goals, organizations execute business processes, which require effective allocation of resources to process activities. This results in the decision-making problem: Which resources should be allocated to which process activities? This problem significantly impacts both process efficiency and effectiveness. Over the past decades, various system-initiated (largely automated) resource allocation approaches have been developed. This study presents a comprehensive overview of this field by analyzing 61 primary studies identified through a rigorous, structured literature review covering publications from 1995 to 2023. We investigate resource allocation goals and cardinalities and describe how process models, execution data, and task attributes, as well as resource attributes, are used to specify the resource allocation problem. Additionally, the type of algorithmic solution and evaluation methods are discussed. This study shows that most approaches support 1-to-1 allocation cardinalities only, specify process-oriented goals, focus on process models, and utilize rule-based methods. Based on the results, we call for future research to define common terminology, support evidence-oriented resource allocation and adaptability, and improve reproducibility and comparability by performing benchmarking studies.

Abstract Large language models (LLMs) have been touted to enable increased productivity in many areas of today's work life. Scientific research as an area of work is no exception: The potential of LLM‐based tools to assist in the daily work of scientists has become a highly discussed topic across disciplines. However, we are only at the very onset of this subject of study. It is still unclear how the potential of LLMs will materialize in research practice. With this study, we give first empirical evidence on the use of LLMs in the research process. We have investigated a set of use cases for LLM‐based tools in scientific research and conducted a first study to assess to which degree current tools are helpful. In this position paper, we report specifically on use cases related to software engineering, specifically, on generating application code and developing scripts for data analytics and visualization. While we studied seemingly simple use cases, results across tools differ significantly. Our results highlight the promise of LLM‐based tools in general, yet we also observe various issues, particularly regarding the integrity of the output these tools provide.

Abstract In order to better facilitate the need for continuous business process improvement, the application of DevOps principles has been proposed. In particular, the AB-BPM methodology applies AB testing—a DevOps practice—and reinforcement learning to increase the speed and quality of business process improvement efforts. In this paper, we provide an industry perspective on this approach, assessing prerequisites, suitability, requirements, risks, and additional aspects of the AB-BPM methodology and supporting tools. Our qualitative study follows the grounded theory research methodology, including 16 semi-structured interviews with BPM practitioners. The main findings indicate: (1) a need for expert control during reinforcement learning-driven experiments in production, (2) the importance of involving the participants and aligning the method culturally with the respective setting, (3) the necessity of an integrated process execution environment, and (4) the long-term potential of the methodology for effective and efficient validation of algorithmically (co-)created business process variants, and their continuous management.

Payment Channel Networks (PCNs) are a promising approach to overcome scalability issues of blockchains. To achieve efficient payments in PCNs, it is necessary to route transactions between a payer and a payee. Especially in large-scale PCNs, multi-hop routing becomes necessary, since transactions need to be relayed by nodes. For this, a scalable routing algorithm is needed, which fits the individual objectives of PCN users. In this article, we study whether routing protocols from the field of Wireless Sensor Networks can be applied in PCNs. To this end, we first derive requirements for routing in PCNs, select suitable approaches, and analyze to which degrees they perform well and meet the requirements. We adapt selected protocols and evaluate them with regard to the lengths of payment paths, fees, and success ratio.

The IEEE International Conference on Software Architecture is the premier venue for practitioners and researchers interested in software architecture, in component-based software engineering and in quality aspects of software and how these relate to the design of software. ICSA has a strong tradition as a working conference, where researchers meet practicing software architects who can explain the problems they face in their day-to-day duties, and who can influence the future of the field.

The design and analysis of process models is a critical factor for organizational improvement across various industries. Thanks to its potential to enable common understanding and foster automation, process modeling is increasingly adopted in the healthcare sector. However, the complexity of the healthcare domain makes process modeling a challenging task, potentially explaining the modest uptake of process modeling standards like the Business Process Model and Notation (BPMN). In this paper, we identify common challenges of process modeling in healthcare, elicited from healthcare process modeling initiatives and supported by the literature. For each challenge, we present some BPMN best practices in the form of ready-to-use process fragments that guide the standard modeling of complex healthcare aspects. Also, we report the results of a first evaluation of the use and perceived usefulness of best practices conducted with junior experts in medicine and IT. We observed that the domain-specific process fragments help to capture healthcare aspects in detail and are perceived as a source of learning, turning out to be especially useful for modelers with a basic understanding of BPMN and the healthcare domain.

Blockchains have been applied in different domains to guarantee data integrity and provide a decentralized computational infrastructure for executing smart contracts. Multiple blockchain-related patterns have been summarized by academics and industry practitioners covering different aspects, such as engineering applications on top of a blockchain, structuring smart contracts, and security. The existence of these patterns is both helpful and challenging for designers. Helpful, as the existence of these patterns means that developers do not need to recreate solutions to common problems. Challenging, as the multitude of patterns leaves a designer confused about when to adopt or adapt patterns. In this paper, we propose a decision model that assists developers and architects in selecting appropriate patterns for blockchain-based applications. The selection is based on the characteristics of the use cases and trade-offs implicit in the patterns. We evaluated the proposed decision model based on expert opinion regarding its correctness and usefulness in guiding the architecture design and understanding the rationale of various design decisions.

Abstract Blockchain has attracted broad interests to build decentralised applications. A typical class of applications uses blockchain for the management of cross‐organisational business processes as well as assets. However, developing such applications without introducing vulnerabilities is hard for developers, not the least because the deployed code is immutable and can be called by anyone with access to the network. Model‐driven engineering (MDE) helps to reduce those risks, by combining proven code snippets as per the model specification, which is easier to understand than source code. Therefore, in this article, we present an approach for integrated MDE across business processes and asset management (e.g., for settlement). Our approach includes methods for fungible/non‐fungible asset registration, escrow for conditional payment, and asset swap. The proposed MDE approach is implemented in a smart contract generation tool called Lorikeet, and evaluated in terms of feasibility, functional correctness, and cost effectiveness.

Human-induced faults play a large role in systems reliability. In cloud platforms, system administrators may inadvertently make catastrophic mistakes, like deleting a virtual disk with important data. Providing rollback for cloud operations can reduce the severity and impact of such mistakes, by allowing to revert to a known, good state. However, in the context of cloud management this is non-trivial, since cloud consumers only have limited visibility and indirect control. In this paper, we present a scalable approach to rollback operations that change the state of a system on proprietary cloud platforms. In our previous work, we provided a system that augments cloud APIs and provides rollback operation using an AI planner. In this paper, we build upon our previous work, but parallelize the rollback plan generation based on characteristics unique to rollback scenario. Furthermore, we introduce a distributed anytime algorithm that gradually improves plan quality overtime, until either an optimal plan is found or a timeout is reached. Through experimental evaluation we show that our approach scales better than a naive approach, and effectively avoids the exponential behavior of AI planning. Further, we explore the trade-offs between the quality of rollback plans and plan generation time.

Blockchain technology provides a tamper-proof mechanism to execute inter-organizational business processes involving mutually untrusted parties. Existing approaches to blockchain-based process execution are based on code generation. In these approaches, a process model is compiled into one or more smart contracts, which are then deployed on a blockchain platform. Given the immutability of the deployed smart contracts, these compiled approaches ensure that all process instances conform to the process model. However, this advantage comes at the price of inflexibility. Any changes to the process model require the redeployment of the smart contracts (a costly operation). In addition, changes cannot be applied to running process instances. To address this lack of flexibility, this paper presents an interpreter of BPMN process models based on dynamic data structures. The proposed interpreter is embedded in a business process execution system with a modular multi-layered architecture, supporting the creation, execution, monitoring and dynamic update of process instances. For efficiency purposes, the interpreter relies on compact bitmap-based encodings of process models. An experimental evaluation shows that the proposed interpreted approach achieves comparable or lower costs relative to existing compiled approaches.

Blockchain has attracted a broad range of interests from start-ups, enterprises and governments to build next generation applications in a decentralized manner. Similar to cloud platforms, a single blockchain-based system may need to serve multiple tenants simultaneously. However, design of multi-tenant blockchain-based systems is challenging to architects in terms of data and performance isolation, as well as scalability. First, tenants must not be able to read other tenants' data and tenants with potentially higher workload should not affect read/write performance of other tenants. Second, multi-tenant blockchain-based systems usually require both scalability for each individual tenant and scalability with number of tenants. Therefore, in this paper, we propose a scalable platform architecture for multi-tenant blockchain-based systems to ensure data integrity while maintaining data privacy and performance isolation. In the proposed architecture, each tenant has an individual permissioned blockchain to maintain their own data and smart contracts. All tenant chains are anchored into a main chain, in a way that minimizes cost and load overheads. The proposed architecture has been implemented in a proof-of-concept prototype with our industry partner, Laava ID Pty Ltd (Laava). We evaluate our proposal in a three-fold way: fulfilment of the identified requirements, qualitative comparison with design alternatives, and quantitative analysis. The evaluation results show that the proposed architecture can achieve data integrity, performance isolation, data privacy, configuration flexibility, availability, cost efficiency and scalability.

Summary Blockchain platforms, such as Ethereum, allow a set of actors to maintain a ledger of transactions without relying on a central authority and to deploy programs, called smart contracts, that are executed whenever certain transactions occur. These features can be used as basic building blocks for executing collaborative business processes between mutually untrusting parties. However, implementing business processes using the low‐level primitives provided by blockchain platforms is cumbersome and error‐prone. In contrast, established business process management systems (BPMSs), such as those based on the standard Business Process Model and Notation (BPMN), provide convenient abstractions for rapid development of process‐oriented applications. This article demonstrates how to combine the advantages of a BPMS with those of a blockchain platform. The article introduces a blockchain‐based BPMN execution engine, named Caterpillar. Like any BPMN execution engine, Caterpillar supports the creation of instances of a process model and allows users to monitor the state of process instances and to execute tasks thereof. The specificity of Caterpillar is that the state of each process instance is maintained on the (Ethereum) blockchain and the workflow routing is performed by smart contracts generated by a BPMN‐to‐Solidity compiler. The Caterpillar compiler supports a large array of BPMN constructs, including subprocesses, multiple‐instance activities, and event handlers. The paper describes the architecture of Caterpillar and the interfaces it provides to support the monitoring of process instances, the allocation and execution of work items, and the execution of service tasks.

Privacy-preserving data analytics is an emerging technology which allows multiple parties to perform joint data analytics without disclosing source data to each other or a trusted third-party. A variety of platforms and protocols have been proposed in this domain. However, these systems are not yet widely used, and little is known about them from a software architecture and performance perspective. Here we investigate the feasibility of using architectural performance modelling and simulation tools for predicting the performance of privacy-preserving data analytics systems. We report on a lab-based experimental study of a privacy-preserving credit scoring application that uses an implementation of a partial homomorphic encryption scheme. The main experiments are on the impact of analytic problem size (number of data items and number of features), and cryptographic key length for the overall system performance. Our modelling approach performed with a relative error consistently under 5\% when predicting the median learning time for the scoring application. We find that the use of this approach is feasible in this technology domain, and discuss how it can support architectural decision making on trade-offs between properties such as performance, cost, and security. We expect this to enable the evaluation and optimisation of privacy-preserving data analytics technologies.

No abstract available.

Blockchain is of rising importance as a technology for engineering applications in cross-organizational settings, avoiding reliance on central trusted third-parties. The use of blockchain, instead of traditional databases or services, is an architectural choice in the development of a software system. The costs of execution and storage are important non-functional qualities, but as yet very little has been done to study them for blockchain-based systems. We investigate the cost of using blockchain using business process execution as a lens. Specifically, we compare the cost for computation and storage of business process execution on blockchain vs. a popular cloud service. First, we capture the cost models for both alternatives. Second, we implemented and measured the cost of business process execution on blockchain and cloud services for an example business process model from the literature. We observe two orders of magnitude difference in this cost.

Blockchain is an emerging technology for decentralised and transactional data sharing across a large network of untrusted participants. It enables new forms of distributed software architectures, where agreement on shared states can be established without trusting a central integration point. A major difficulty for architects designing applications based on blockchain is that the technology has many configurations and variants. Since blockchains are at an early stage, there is little product data or reliable technology evaluation available to compare different blockchains. In this paper, we propose how to classify and compare blockchains and blockchain-based systems to assist with the design and assessment of their impact on software architectures. Our taxonomy captures major architectural characteristics of blockchains and the impact of their principal design decisions. This taxonomy is intended to help with important architectural considerations about the performance and quality attributes of blockchain-based systems.

Blockchain is an emerging technology for sharing transactional data and computation without using a central trusted third party. It is an architectural choice to use a blockchain instead of traditional databases or protocols, and this creates trade-offs between non-functional requirements such as performance, cost, and security. However, little is known about predicting the behaviour of blockchain-based systems. This paper shows the feasibility of using architectural performance modelling and simulation tools to predict the latency of blockchain-based systems. We use established tools and techniques, but explore new blockchain-specific issues such as the configuration of the number of confirmation blocks and inter-block times. We report on a lab-based experimental study using an incident management system, showing predictions of median system level response time with a relative error mostly under 10%. We discuss how the approach can be used to support architectural decision-making, during the design of blockchain-based systems.

Blockchain has recently gained momentum. Startups, enterprises, banks, and government agencies around the world are exploring the use of blockchain for broad applications including public registries, supply chains, health records, and voting. Dependability properties, like availability, are critical for many of these applications, but the guarantees offered by the blockchain technology remain unclear, especially from an application perspective. In this paper, we identify the availability limitations of two mainstream blockchains, Ethereum and Bitcoin. We demonstrate that while read availability of blockchains is typically high, write availability - for transaction management - is actually low. For Ethereum, we collected 6 million transactions over a period of 97 days. First, we measured the time for transactions to commit as required by the applications. Second, we observed that some transactions never commit, due to the inherent blockchain design. Third and perhaps even more dramatically, we identify the consequences of the lack of built-in options for explicit abort or retry that can maintain the application in an uncertain state, where transactions remain pending (neither aborted nor committed) for an unknown duration. Finally we propose techniques to mitigate the availability limitations of existing blockchains, and experimentally test the efficacy of these techniques.

Cloud-based systems get changed more frequently than traditional systems. These frequent changes involve sporadic operations such as installation and upgrade. Sporadic operations may fail due to the uncertainty of cloud platforms. Each sporadic operation manipulates a number of cloud resources. The accessibility of resources manipulated makes it possible to build an accurate process model of the correct behavior for an operation and its desired effects. This paper proposes a non-intrusive recovery approach for sporadic operations on cloud, called POD-Recovery. POD-Recovery utilizes the above-mentioned process model of the operation. When needed, it triggers recovery actions based on the model through non-intrusive means, i.e., without modifying the code which implements the sporadic operation. POD-Recovery employs an efficient artificial intelligence (AI) planning technique for generating recovery plans. We implement POD-Recovery and evaluate it by recovering from faults injected into 920 runs of five representative sporadic operations.

Understanding the behavior of an operations process and capturing it as an abstract process model has been shown to improve dependability significantly [1]. In particular, process context can be used for error detection, diagnosis, and even automated recovery. Creating the process model is an essential step in determining process context and, consequently, improving dependability. This paper describes two systems. The first, POD-Discovery, simplifies the creation of such an abstract process model from operations logs. An activity that previously required many manual steps can now be done largely automatically and in minutes. Using the discovered model, the second system, POD-Viz, provides operators with the ability to visualize the current state of an operations process in near-real-time and to replay a set of events to understand how the process context changed over time. This allows operators to trace the progress of an operations process easily, and helps in analyzing encountered errors.

Failure of application operations is one of the main causes of system-wide outages in cloud environments. This particularly applies to DevOps operations, such as backup, redeployment, upgrade, customized scaling, and migration that are exposed to frequent interference from other concurrent operations, configuration changes, and resources failure. However, current practices fail to provide a reliable assurance of correct execution of these kinds of operations. In this paper, we present an approach to address this problem that adopts a regression-based analysis technique to find the correlation between an operation's activity logs and the operation activity's effect on cloud resources. The correlation model is then used to derive assertion specifications, which can be used for runtime verification of running operations and their impact on resources. We evaluated our proposed approach on Amazon EC2 with 22 rounds of rolling upgrade operations while other types of operations were running and random faults were injected. Our experiment shows that our approach successfully managed to raise alarms for 115 random injected faults, with a precision of 92.3%.

Applications in the cloud are subject to sporadic changes due to operational activities such as upgrade, redeployment, and on-demand scaling. These operations are also subject to interferences from other simultaneous operations. Increasing the dependability of these sporadic operations is non-trivial, particularly since traditional anomaly-detection-based diagnosis techniques are less effective during sporadic operation periods. A wide range of legitimate changes confound anomaly diagnosis and make baseline establishment for "normal" operation difficult. The increasing frequency of these sporadic operations (e.g. due to continuous deployment) is exacerbating the problem. Diagnosing failures during sporadic operations relies heavily on logs, while log analysis challenges stemming from noisy, inconsistent and voluminous logs from multiple sources remain largely unsolved. In this paper, we propose Process Oriented Dependability (POD)-Diagnosis, an approach that explicitly models these sporadic operations as processes. These models allow us to (i) determine orderly execution of the process, and (ii) use the process context to filter logs, trigger assertion evaluations, visit fault trees and perform on-demand assertion evaluation for online error diagnosis and root cause analysis. We evaluated the approach on rolling upgrade operations in Amazon Web Services (A WS) while performing other simultaneous operations. During our evaluation, we correctly detected all of the 160 injected faults, as well as 46 interferences caused by concurrent operations. We did this with 91.95% precision. Of the correctly detected faults, the accuracy rate of error diagnosis is 96.55%.

Business processes orchestrate service requests in a structured fashion. Process knowledge, however, has rarely been used to predict and decide about cloud infrastructure resource usage. In this paper, we present an approach for BPM-aware cloud computing that builds on process knowledge to improve the timeliness and quality of resource scaling decisions. We introduce an IaaS resource controller based on fuzzy theory that monitors process execution and that is used to predict and control resource requirements for subsequent process tasks. In a laboratory experiment, we evaluate the controller design against a commercially available state-of-the-art auto scaler. Based on the results, we discuss improvements and limitations, and suggest directions for further research.

In many cases, it is not cost effective to automate business processes which affect a small number of people and/or change frequently. We present a novel approach for enabling domain experts to model and deploy such processes from their respective domain as Web service compositions. The approach builds on user-editable service, naming and representing Web services as forms. On this basis, the approach provides a visual composition language with a targeted restriction of control-flow expressivity, process simulation, automated process verification mechanisms, and code generation for executing orchestrations. A Web-based service composition prototype implements this approach, including a WS-BPEL code generator. A small lab user study with 14 participants showed promising results for the usability of the system, even for nontechnical domain experts.

Planning is concerned with the automated solution of action sequencing problems described in declarative languages giving the action preconditions and effects. One important application area for such technology is the creation of new processes in Business Process Management (BPM), which is essential in an ever more dynamic business environment. A major obstacle for the application of Planning in this area lies in the modeling. Obtaining a suitable model to plan with -- ideally a description in PDDL, the most commonly used planning language -- is often prohibitively complicated and/or costly. Our core observation in this work is that this problem can be ameliorated by leveraging synergies with model-based software development. Our application at SAP, one of the leading vendors of enterprise software, demonstrates that even one-to-one model re-use is possible. The model in question is called Status and Action Management (SAM). It describes the behavior of Business Objects (BO), i.e., large-scale data structures, at a level of abstraction corresponding to the language of business experts. SAM covers more than 400 kinds of BOs, each of which is described in terms of a set of status variables and how their values are required for, and affected by, processing steps (actions) that are atomic from a business perspective. SAM was developed by SAP as part of a major model-based software engineering effort. We show herein that one can use this same model for planning, thus obtaining a BPM planning application that incurs no modeling overhead at all. We compile SAM into a variant of PDDL, and adapt an off-the-shelf planner to solve this kind of problem. Thanks to the resulting technology, business experts may create new processes simply by specifying the desired behavior in terms of status variable value changes: effectively, by describing the process in their own language.

In several application areas for Planning, in particular helping with the creation of new processes in Business Process Management (BPM), a major obstacle lies in the modeling. Obtaining a suitable model to plan with is often prohibitively complicated and/or costly. Our core observation in this work is that, for software-architectural purposes, SAP is already using a model that is essentially a variant of PDDL. That model describes the behavior of Business Objects, in terms of status variables and how they are affected by system transactions. We show herein that one can leverage the model to obtain (a) a promising BPM planning application which incurs hardly any modeling costs, and (b) an interesting planning benchmark. We design a suitable planning formalism and an adaptation of FF, and we perform large-scale experiments. Our prototype is part of a research extension to the SAP NetWeaver platform.

In this paper we present FormSys, a Web-based system that service-enables form documents. It offers two main services: filling in forms based on Web services' incoming SOAP messages, and invoking Web services based on filled-in forms. This can be applied to benefit individuals to reduce the number of often repetitive form fields they have to complete manually in many scenarios. It can also help organisations to remove the need for manual data entry by automatically triggering business process implementations based on incoming case data from filled-in forms. While the concept applies to forms of any type of document, our implementation uses Adobe AcroForms due to its universal applicability, availability of a usable API, and end-user appeal. In the demo, we will show the two core functions, namely soap2pdf and pdf2soap, along with use case applications of the services developed from real world scenarios. Essentially, this work demonstrates how PDFs can be used as a channel for interacting with Web services.

This paper proposes a model-based technique for lowering the entrance barrier for service providers to register services with a marketplace broker, such that the service is rapidly configured to utilize the brokerpsilas local service delivery management components. Specifically, it uses process modeling for supporting the execution steps of a service and shows how service delivery functions (e.g. payment points) ldquolocalrdquo to a service broker can be correctly configured into the process model. By formalizing the different operations in a service delivery function (like payment or settlement) and their allowable execution sequences (full payments must follow partial payments), including cross-function dependencies, it shows how through tool support, the non-technical user can quickly configure service delivery functions in a consistent and complete way.

Automatic Web service composition (WSC) is a key component of flexible SOAs. We address WSC at the profile/capability level, where preconditions and effects of services are described in an ontology. In its most expressive formulation, WSC has two sources of complexity: (A) a combinatorial explosion of the services composition space, and (B) worst-case exponential reasoning is needed to determine whether the underlying ontology implies that a particular composition is a solution. Any WSC technology must hence choose a trade-off between scalability and expressivity. We devise new methods for finding better trade-offs. We address (A) by techniques for the automatic generation of heuristic functions. We address (B) by approximate reasoning techniques for the fully expressive case, and by identifying a sub-class where the required reasoning is tractable. We show empirically that our approach scales gracefully to large pools of pre-discovered services, in several test cases.